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Full Discussion: Explanation on egrep
Top Forums UNIX for Dummies Questions & Answers Explanation on egrep Post 302594740 by Skrynesaver on Wednesday 1st of February 2012 05:20:30 AM
Old 02-01-2012
Reqular expressions use the square brackets to indicate a character range, the backslash \ is used to escape the following character, thus preventing the regex engine from interpreting it as the beginning of a range.

If it is not included the grep will fail with an error similar to grep: Unmatched [ or [^.
 

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ZGREP(1)						      General Commands Manual							  ZGREP(1)

NAME
zgrep - search possibly compressed files for a regular expression SYNOPSIS
zgrep [ grep_options ] [ -e ] pattern filename... DESCRIPTION
Zgrep is used to invoke the grep on compress'ed or gzip'ed files. All options specified are passed directly to grep. If no file is speci- fied, then the standard input is decompressed if necessary and fed to grep. Otherwise the given files are uncompressed if necessary and fed to grep. If zgrep is invoked as zegrep or zfgrep then egrep or fgrep is used instead of grep. If the GREP environment variable is set, zgrep uses it as the grep program to be invoked. For example: for sh: GREP=fgrep zgrep string files for csh: (setenv GREP fgrep; zgrep string files) AUTHOR
Charles Levert (charles@comm.polymtl.ca) SEE ALSO
grep(1), egrep(1), fgrep(1), zdiff(1), zmore(1), znew(1), zforce(1), gzip(1), gzexe(1) ZGREP(1)
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